1. Field of the Invention
Embodiments described herein relate to air handling systems utilizing air treatment. More particularly, embodiments described herein relate to filter holding frame assemblies and flexible retainers for securing filters in the air handling systems.
2. Description of the Related Art
Air filtration systems typically utilize filter holding frames, interchangeably referred to as “holding frames”, to secure various combinations of pre-filtration and final filtration elements into an air duct of an air handling system. Filter holding frames, such as Type 8 holding frames available from Camfil Farr, Inc., of Riverdale, N.J., may be used with a variety of fasteners to allow the installation of the various combinations of pre-filtration and final filtration elements. Typically, the fasteners may include any combination of clips, clamps, springs, wires, and/or brackets.
Conventionally, filter holding frames for filtration elements generally use some type of mechanical clamping mechanism. This mechanism is utilized to effectively secure the filtration element to the filter holding frame positioned within the air duct and reduce any bypass or leakage around the filtration element. For example, a HEPA filter with an efficiency of 99.97% has a maximum allowable penetration of 0.03%. In such high efficiency applications, a gasket is typically employed between the filtration element and filter holding frame to effectively prevent bypass of the filtration element. The same methods also occur in medium and low efficiency filtration systems; gaskets are used to minimize bypass between the filtration element and the holding frame.
The need to have clamping devices to seal final filtration elements and various types of fasteners to secure and hold prefilters results in a very time consuming and costly process when filters must be removed and/or installed. This is particularly true on large filtration systems where dozens, if not hundreds, of filters must be removed and replaced on a regular basis. The use of wrenches, ratchets, or other types of tools is often required in order to loosen nuts, bolts, or other fasteners in order to remove the filters from the filter holding frames or to loosen the filter clamping mechanisms.
Additionally, a filter of a particular type and/or size may require a corresponding fastener, such as a particularly sized clip, that is specifically configured to secure the particular filter to the filter holding frame. Securing a filter element to the filter holding frame results in a laborious process to correctly locate a fastener that corresponds to the filter element from a collection of fasteners maintained for filtration systems using diverse types and sizes of filter elements. Further, a fastener typically engages with a set of mating bosses or lances formed through the filter holding frame to secure a filter element. To accommodate a wide variety of fasteners, multiple sets of bosses or lances are formed through the filter holding frame, resulting in additional labor and cost, even though many sets of holes may go unused.
Thus, there is a need for a filter holding frame assembly with a retention mechanism that does not require the use of tools to operate, that can be used to effectively secure prefilters, low-, and medium-efficiency filters in the filter holding frame and that reduces need to support a fragmented marketplace of fasteners.